Dual valve fluid actuator assembly

Abstract

A stage assembly ( 10 ) includes a stage ( 14 ), and a fluid actuator assembly ( 24 ) that moves the stage ( 14 ). The fluid actuator assembly ( 24 ) includes a piston housing ( 32 ) that defines a piston chamber ( 34 ); (ii) a piston ( 36 ) that separates the piston chamber ( 34 ) into a first chamber ( 34 A) and a second chamber ( 34 B); (iii) a supply valve ( 38 C) that controls the flow of the working fluid ( 40 ) into the first chamber ( 34 A); and (iv) an exhaust valve ( 38 D) that controls the flow of the working fluid ( 40 ) out of the first chamber ( 34 A). The supply valve ( 38 C) has a supply orifice ( 250 G) having a supply orifice area, and the exhaust valve ( 38 D) has an exhaust orifice ( 352 G) having an exhaust orifice area. Moreover, the supply orifice area is different from the exhaust orifice area. Further multiple valves of different sizes can be used in combination for the supply and exhaust for each chamber ( 34 A), ( 34 B).

What is claimed is: 
     
       1. A stage assembly for positioning a workpiece along a movement axis, the stage assembly comprising:
 a stage that is adapted to couple to the workpiece; 
 a base; 
 a fluid actuator assembly that is coupled to and moves the stage along the movement axis relative to the base, the fluid actuator assembly including (i) a piston housing that defines a piston chamber; (ii) a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston; and (iii) a first valve sub-assembly that includes a first supply valve that controls the flow of the working fluid into the first chamber, and a first exhaust valve that controls the flow of the working fluid out of the first chamber; 
 wherein the first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area; wherein the first supply orifice area is different from the first exhaust orifice area; 
 a control system that controls the fluid actuator assembly to control the flow of the working fluid into and out of the first chamber; and 
 a second valve sub-assembly that controls the flow of the working fluid into and out of the second chamber; wherein the second valve sub-assembly includes a first supply valve that controls the flow of the working fluid into the second chamber, and a first exhaust valve that controls the flow of the working fluid out of the second chamber; wherein the first supply valve of the second valve sub-assembly has a first supply orifice having a first supply orifice area, and the first exhaust valve of the second valve sub-assembly has a first exhaust orifice having a first exhaust orifice area; wherein, for the second valve sub-assembly, the first exhaust orifice area is larger than the first supply orifice area. 
 
     
     
       2. The stage assembly of  claim 1  wherein, for the first valve sub-assembly, the first exhaust orifice area is larger than the first supply orifice area. 
     
     
       3. The stage assembly of  claim 1  wherein, for the first valve sub-assembly, the first exhaust orifice area is at least one hundred percent larger than the first supply orifice area. 
     
     
       4. The stage assembly of  claim 1  wherein, for the second valve sub-assembly, the first exhaust orifice area is at least one hundred percent larger than the first supply orifice area. 
     
     
       5. The stage assembly of  claim 4  wherein, for each valve sub-assembly, the first exhaust orifice area is at least ten percent larger than the first supply orifice area. 
     
     
       6. The stage assembly of  claim 1  wherein the first valve sub-assembly includes a second supply valve that controls the flow of the working fluid into the first chamber; wherein the second supply valve has a second supply orifice having a second supply orifice area; and the second supply orifice area is larger than the first supply orifice area. 
     
     
       7. The stage assembly of  claim 6  wherein the first valve sub-assembly includes a second exhaust valve that controls the flow of the working fluid out of the first chamber; wherein the second exhaust valve has a second exhaust orifice having a second exhaust orifice area; and the first exhaust orifice area is larger than the second exhaust orifice area. 
     
     
       8. The stage assembly of  claim 1  wherein each valve is a proportional valve. 
     
     
       9. An exposure apparatus including an illumination source that generates an illumination beam, and the stage assembly of  claim 1  that moves the stage relative to the illumination beam. 
     
     
       10. A method for positioning a workpiece along a movement axis, the method comprising:
 providing a base; 
 coupling the workpiece to a stage; 
 moving the stage along the movement axis relative to the base with a fluid actuator assembly that includes (i) a piston housing that defines a piston chamber; (ii) a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston; and (iii) a first valve sub-assembly that controls the flow of a working fluid into the first chamber, the first valve sub-assembly including a first supply valve that controls the flow of the working fluid into the first chamber, and a first exhaust valve that controls the flow of the working fluid out of the first chamber; wherein the first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area; wherein the first supply orifice area is different from the first exhaust orifice area; and 
 controlling the fluid actuator assembly with a control system to control the flow of the working fluid into and out of the first chamber, 
 wherein the step of moving includes providing a second valve sub-assembly that controls the flow of the working fluid into and out of the second chamber; wherein the second valve sub-assembly includes a first supply valve that controls the flow of the working fluid into the second chamber, and a first exhaust valve that controls the flow of the working fluid out of the second chamber; wherein the first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area; wherein, for the second valve sub-assembly, the first exhaust orifice area is larger than the first supply orifice area. 
 
     
     
       11. The method of  claim 10  wherein the step of moving includes, for the first valve sub-assembly, the first exhaust orifice area being larger than the first supply orifice area. 
     
     
       12. The method of  claim 10  wherein the step of moving includes, for the first valve sub-assembly, the first exhaust orifice area being at least ten percent larger than the first supply orifice area. 
     
     
       13. The method of  claim 10  wherein the step of providing includes, for the second valve sub-assembly, the first exhaust orifice area being at least one hundred percent larger than the first supply orifice area. 
     
     
       14. The method of  claim 13  wherein the step of providing includes, for each valve sub-assembly, the first exhaust orifice area being at least one hundred percent larger than the first supply orifice area. 
     
     
       15. The method of  claim 10  wherein the step of moving includes the first valve sub-assembly having a second supply valve that controls the flow of the working fluid into the first chamber; wherein the second supply valve has a second supply orifice having a second supply orifice area; and the second supply orifice area is larger than the first supply orifice area. 
     
     
       16. The method of  claim 15  wherein the step of moving includes the first valve sub-assembly having a second exhaust valve that controls the flow of the working fluid out of the first chamber; wherein the second exhaust valve has a second exhaust orifice having a second exhaust orifice area; and the first exhaust orifice area is larger than the second exhaust orifice area. 
     
     
       17. The method of  claim 10  wherein the step of moving includes each valve being a proportional valve. 
     
     
       18. A method for exposing a workpiece comprising the steps of providing an illumination source that generates an illumination beam, and moving the workpiece relative to the illumination beam with the stage assembly of  claim 10 . 
     
     
       19. A stage assembly for positioning a workpiece along a movement axis, the stage assembly comprising:
 a stage that is adapted to couple to the workpiece; 
 a base; 
 a fluid actuator assembly that is coupled to and moves the stage along the movement axis relative to the base, the fluid actuator assembly including (i) a piston housing that defines a piston chamber; (ii) a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston; and (iii) a first valve sub-assembly that controls the flow of a working fluid into the first chamber, the first valve sub-assembly including a plurality of first supply valves that control the flow of the working fluid into the first chamber, and a plurality of first exhaust valves that control the flow of the working fluid out of the first chamber; 
 a control system that controls the fluid actuator assembly to control the flow of the working fluid into and out of the first chamber; and 
 a second valve sub-assembly that controls the flow of the working fluid into and out of the second chamber; wherein the second valve sub-assembly includes a plurality of second supply valves that control the flow of the working fluid into the second chamber, and a plurality of second exhaust valves that control the flow of the working fluid out of the second chamber. 
 
     
     
       20. A stage assembly for positioning a workpiece along a movement axis, the stage assembly comprising:
 a stage that is adapted to couple to the workpiece; 
 a base; 
 a fluid actuator assembly that is coupled to and moves the stage along the movement axis relative to the base, the fluid actuator assembly including (i) a piston housing that defines a piston chamber; (ii) a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston; and (iii) a first valve sub-assembly that includes a first supply valve that controls the flow of the working fluid into the first chamber, and a first exhaust valve that controls the flow of the working fluid out of the first chamber; 
 wherein the first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area; wherein the first supply orifice area is different from the first exhaust orifice area; and 
 a control system that controls the fluid actuator assembly to control the flow of the working fluid into and out of the first chamber, 
 wherein the first valve sub-assembly includes a second supply valve that controls the flow of the working fluid into the first chamber; wherein the second supply valve has a second supply orifice having a second supply orifice area; and 
 the second supply orifice area is larger than the first supply orifice area. 
 
     
     
       21. A method for positioning a workpiece along a movement axis, the method comprising:
 providing a base; 
 coupling the workpiece to a stage; 
 moving the stage along the movement axis relative to the base with a fluid actuator assembly that includes (i) a piston housing that defines a piston chamber; 
 (ii) a piston that is positioned within and moves relative to the piston chamber along a piston axis, the piston separating the piston chamber into a first chamber and a second chamber that are on opposite sides of the piston; and (iii) a first valve sub-assembly that controls the flow of a working fluid into the first chamber, the first valve sub-assembly including a first supply valve that controls the flow of the working fluid into the first chamber, and a first exhaust valve that controls the flow of the working fluid out of the first chamber; wherein the first supply valve has a first supply orifice having a first supply orifice area, and the first exhaust valve has a first exhaust orifice having a first exhaust orifice area; wherein the first supply orifice area is different from the first exhaust orifice area; and 
 controlling the fluid actuator assembly with a control system to control the flow of the working fluid into and out of the first chamber, 
 wherein the step of moving includes the first valve sub-assembly having a second supply valve that controls the flow of the working fluid into the first chamber; 
 wherein the second supply valve has a second supply orifice having a second supply orifice area; and the second supply orifice area is larger than the first supply orifice area.